House Intelligence Committee Chairman Mike Rogers said Wednesday there was a “high probability” the Syrian government had used chemical weapons during a battle in Aleppo earlier this week, and said a failure to act by the U.S. would be a “stain on our national character.”

“There’s a high probability that a chemical agent was used in Aleppo,” Rogers said on CBS’s “This Morning.” “I’m an old FBI guy. I like to see forensic evidence.”

A U.S. official told The Associated Press on Tuesday that neither side had used chemical weapons in a battle near Aleppo. The Russian government, which has backed the regime of dictator Bashar Assad in the conflict, accused the Syrian rebels of using chemical weapons, a charge the U.S. government rejected.

Syria has one of the world’s largest stockpiles of chemical weapons, and President Barack Obama has declared their use to be a “red line” that would lead to a U.S. military intervention.

Rogers said the United States needed to “remove” the regime’s “capability to use chemical weapons on civilians” in order to restore its credibility with rebel groups, but said that wouldn’t involve putting troops on the ground. Rogers wasn’t specific about alternatives, saying: “I don’t want to talk about all our capabilities.”

“If we know their intention to use these chemical weapons and don’t do anything about that, that is a stain on our national character,” Rogers said. “So we’ve got a growing bloody conflict, you’ve got a regime that’s under pressure, at least a high probability they have used most recently or in the past some amount of chemical weapons. This is the time to act. Don’t wait until we have 5,000 dead. That’s too late.”